1. Field of the Invention
The present invention relates to an ink composition and an ink jet recording method using the same.
2. Background Art
An ink for use in an ink jet recording system generally comprises a solution of various dyes dissolved in water or an Organic solvent or a mixture thereof. In inks used in ink jet recording, however, various property requirements are more strict than those for inks used in writing utensils such as fountain pens and ball-point pens.
Properties required of the ink for ink Jet recording include that physical properties such as viscosity and surface tension are suitable; the optical density is high; sharp color tone and image can be provided; an image excellent in fastness properties, such as water resistance and light-fastness, can be provided; the Storage stability is excellent; clogging of nozzles is less likely to occur, and the scent and stability are good.
Most of these properties are satisfied by using a water-base ink prepared by dissolving a water-soluble dye in water or a mixture of water with a water-soluble organic solvent. Therefore, improvements have been made in the water-base ink for ink jet printing method.
For example, an attempt to improve the penetration of the ink has been made in order to rapidly fix the ink onto paper. Regarding this, Japanese Patent Laid-Open No. 183761/1992 and U.S. Pat. Nos. 5,183,502 and 5,156,675 disclose the addition of diethylene glycol monobutyl ether and the addition of both a glycol ether and a nonionic acetylene glycol surfactant. However, it is sometimes impossible to realize an excellent color development and image density, i.e., a sharp image, because these inks may well penetrate into paper. In order to solve this problem, increased dye concentration might be effective. However, the high concentration of the dye may increase solid content which may cause precipitation in the vicinity of a nozzle, which is causative of clogging of the nozzle. Further increasing the amount of a wetting agent for preventing clogging of the nozzle increases the viscosity of the ink, which is disadvantageous particularly in the ink jet recording system.
Moreover, since properties of the ink, such as color tone, water resistance, and light fastness, are influenced greatly by the properties of the dye, studies have been made on dyes. Further, there is an ever-increasing demand particularly for water resistance of prints among various ink properties. For example, Japanese Patent Laid-Open Nos. 79681/1991, 91577/1991, 73320/1994, and 172668/1994 disclose that an ink composition having good water resistance can be provided by using a particular dye.
However, there is room for improvement in various properties of these ink compositions.